No issue for me, just a little inconvinience of calling the MPC hotline.
Yes, I was able to select emergecy exits online before the system upgrade, after the upgrade I was able to get an emergency exit seat on all legs 4 tmes already by phone since the upgrade.
The 4th one was due to an aircraft change so I lost that premium seat. I called them again for re-assignment and they placed me back on the emergency exit.
In other airlines, even if you are an elite frequent flier, you still have to pay for it, it is only for million milers that this becomes free..
So I'm ok with it, at least this benefit is still free for CX elite frequent fliers.